292 



A TEXT-BOOK OF BOTANY. 



156). They usually arise as the product of a meristem situated 

 beneath the stomata of the epidermis, the stomata being replaced 

 by them when cork is developed. Several types of lenticels are 



FIG. 157- 



Bark of Rhamnus Pttrsliianus showing large whitish patches of lichens, 

 and numerous lens-shaped lenticels. 



.listinguished. They are quite characteristic and prominent in 

 a number of barks, as those of species of Betula, Prunus, Rham- 

 nus (Fig. 157), etc. 



